ST. LOUIS - A large crowd, some chanting "Hands up, don't shoot," gathered Tuesday at the site where St. Louis police officers shot and killed a knife-wielding man after a reported convenience store robbery.

The shooting happened just a few miles from Ferguson, where the fatal shooting of an unarmed 18-year-old, Michael Brown, by a white police officer has touched off days of sometimes violent protests. The crowd had largely diminished within several hours of the shooting.

St. Louis Police Capt. Ed Kuntz said police responded shortly after noon following a report of a robbery at a convenience store. The suspect, a 23-year-old black man, refused police orders to drop the knife, Kuntz said.

When the man allegedly raised the weapon and moved toward the officers, both opened fire, killing him, said Kuntz.

A man who said he witnessed the shooting, Robert Addison, 36, said the suspect cursed officers as he told them, "You'll have to kill me."

Both officers were placed on administrative duty pending an investigation, but Kuntz said the shooting appeared to be justified.

A crowd of about 100 onlookers gathered at the site within an hour of the shooting. Some chanted "Hands up, don't shoot," which has become the mantra of protesters in Ferguson after witnesses described Brown as having his hands in the air when he was shot Aug. 9.

Ferguson officer Darren Wilson has been on paid administrative leave since the shooting of Brown. The investigation could be turned over to a grand jury as early as Wednesday, though it isn't clear how long it will be before a determination is made about whether Wilson will be charged.